1. Field of the Invention
The present invention relates to a signal receiver, and more particularly, to a signal receiver which can compensate a voltage offset of an input signal to make the DC level at an output node of the signal receiver can keep a constant value, and a related voltage compensation method.
2. Description of the Prior Art
A semiconductor memory can be divided into two categories: a volatile memory, e.g. a dynamic random access memory (DRAM); and a non-volatile memory. The difference between these categories is whether the stored data can be reserved for a long time when external electric power is turned off. The data stored in the DRAM will disappear when the external electric power is turned off but the data stored in the non-volatile memory will be preserved.
Please refer to FIG. 1. FIG. 1 is a diagram showing a problem resulting from voltage offsets of a reference voltage in a signal receiver of a memory module according to the prior art. As shown in FIG. 1, VREF represents a reference voltage in a signal receiver of the memory module, offset reference voltages VREF′ and VREF″ respectively represent the reference voltage VREF having offsets, VIN represents an input signal of the signal receiver, and VOUT represents an output signal after the input signal VIN passes through the signal receiver. If no offset exists in the reference voltage VREF, the output signal VOUT is generated after the input signal VIN passes through the signal receiver. If an offset exists in the reference voltage VREF, such as the offset reference voltage VREF′ or VREF″, the output signal VOUT′ or VOUT″ is generated after the input signal VIN passes through the signal receiver. As can be seen from FIG. 1, if an offset exists in the reference voltage VREF, the duty cycle of the output signal VOUT′/VOUT″ is different from that of the output signal VOUT, which affects the accuracy of accessing data of the memory module.
Hence, how to overcome problems resulting from voltage offsets of the reference voltage in the signal receiver of the memory module has become an important topic of the field.